IE1206 Embedded Electronics

Transcription

1 E06 Embedded Electronics Le Le3 Le4 Le Ex Ex PC-block Documentation, Seriecom Pulse sensors,, R, P, serial and parallel KC LAB Pulse sensors, Menu program Start of programing task Kirchhoffs laws ode analysis Two-terminals RR AD Le5 Ex3 KC LAB Two-terminals, AD, Comparator/Schmitt Le6 Le8 Ex6 Le3 Ex4 Ex5 Le0 Le7 Le9 Le Le Ex7 Display Written exam KC3 LAB3 Transients PWM Step-up, RC-oscillator Phasor jω PWM CCP CAP/D-sensor KC4 LAB4 LP-filter Trafo LC-osc, DC-motor, CCP PWM Display of programing task Trafo, Ethernet contact

2 Transformer

3 Voltage ratio : dφ dt dφ dt

4 deal transformer Magnetisig current 0 0 is small compared to the work currents and. The transformer itself has a high inductance.

5 Current ratio 0 0 ) 0, ( P P P :

6 Eddy current losses Eddy currents currents inside the iron core is prevented with lacquered ( isolation ) sheet metal.

7 E -core E-core is very economical to manufacture!

8 E -core

9 Toroid Toroid core has a low leakage field so it will not disturb nearby electronics! How do one wind such a transformer?

10 Automatic Winding of toroidal core

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12 Transformer (5.4)

13 Transformer (5.4)

14 Transformer (5.4) 0 R 0 0 0, 0 8

15 Transformer (5.4) 8 0 0, R 4 8

16 Transformatorn (5.4) 0 R 0 0 0, , 4

17 Transformer (5.4) 0 R 0 0 0, , 4 R 4 0 Ω 0,4

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19 R R R R R Transforming impedances

20 R R R R R Transforming impedances

21 Ex. Transforming impedances A transformer has the voltage ratio 40V/0V. We have two capacitors µf and 6 µf. How should one connect to get 5 µf?

22 Ex. Transforming impedances A transformer has the voltage ratio 40V/0V. We have two capacitors µf and 6 µf. How should one connect to get 5 µf? Z Z ωc ωc ω( C / 4)

23 Ex. Transforming impedances A transformer has the voltage ratio 40V/0V. We have two capacitors µf and 6 µf. How should one connect to get 5 µf? Z Z ωc ωc ω( C / 4) 4µ F 6µ F

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25 Series and parallel connection of inductors (Ex. 5.6) Assuming that none of the coils parts magnetic lines of force with each other but are completely independent components, they can be treated series and parallel inductors just as if they were resistors. L ERS 3 H

26 Series and parallel connection of inductors? We have previously studied serial and parallel coils as if they were completely independent components that do not share magnetic lines with each other. We are now treating coils with interconnected flow??

27 nductive coupling nduction u r i + dϕ dt A portion of the flow in the coil is interconnected with flow from the coil. dϕ u r i + ϕ i L + i M dt n same way: dϕ u r i + ϕ i L + i M dt

28 nductive coupling ± M is called mutual inductance di di u r i + L + M dt dt di di u r i + L + M dt dt jω-method: r + jω L + jω M r + jω L + jω M An ideal transformer has coupling factor k (00%) Coupling factor: k L M L The coupling factor indicates how much of the flow a coil has in common with another coil

29 Series with mutual inductance Derive: L M L L L M L L ω ± ω ω ± L j L L j M L L j L L j M L ω Series connection has the same current + M M M L L L L jω( L ± M + L ± M ) j ω ( L + L ± M )

30 Series with mutual inductance M-dot M-dot M-dot M-dot Series connection has the same current L TOT L + L M L TOT L + L M + M can can contribute or counter act to the flow, this gives ± sign. Therefore, coil winding polarity is usually indicated by a dot convention in schematics.

31 Dot convention An increasing current in to a dot results in induced voltages with directions that would give increasing currents out of other dots.

32 Dot convention An increasing current in to a dot results in induced voltages with directions that would give increasing currents out of other dots.

33 n parallel with mutual inductance M L L M L L L TOT + M L L M L L L TOT + + TOT L TOT L Parallel connected coils Antiparal conected coils

34 Ex. 5.7 Series connection M 3 [H] M M 3 3 L 5 L 0 L 3 5

35 Ex. 5.7 Series connection M 3 [H] M M 3 3 L 5 L 0 L 3 5 L TOT L + M M 3 + L + M M 3 + L 3 M 3 M [H]

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37 Measuring the mutual inductance? L TOT + L TOT L TOT L + L M + + L TOT L + L M

38 Measuring the mutual inductance? L TOT + L TOT L TOT L + L M + + L TOT L + L M M L TOT + L 4 TOT

39 Variometer (to an antique radio) L TOT L + M f ( α) L ± M

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41 A bad actuator can become a good sensor 906

42 The industry's "rugged" position sensor

43 Differential transformer LVDT Linear Variable Differential Transformer primary coil core secondary coil secondary coil The secondary coils are connected in series but with opposite polarity when the core is in the middle 0.

44 LVDT design

45 LVDT principle The output voltage is relatively high it makes this a popular sensor

46 LVDT probe Output signal changes phase 80 exactly when the core pass the middle point. A XOR-gate kan indicate this change.

47 A LVDT probe can keep track on that the thicknes is correct. Guess application? t is important to ensure that the ATM does not distribute "double" bills

48 Periodic differential transformer A similar sensor? LVDT-principel witin a core, and then keep track on how many cores that have passed. Renywell Spherical encoder

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